Microgreen Variety Impacts Leaf Surface Persistence of a Human Norovirus Surrogate

Food and Environmental Virology - Human norovirus (HuNoV) is a pathogenic agent that is frequently associated with foodborne disease outbreaks linked to fresh produce. Within microgreen production...     

Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone

Food and Environmental Virology - Retail foodservice establishments (FSE) frequently utilize washes with sanitizing agents during fresh produce preparation. This study evaluated the efficacy of...     

Modeling the Potential Impacts of Climate Change on Pacific Salmon Culture Programs: An Example at Winthrop National Fish Hatchery

Hatcheries have long been used in an attempt to mitigate for declines in wild stocks of Pacific salmon (Oncorhynchus spp.), though the conservation benefit of hatcheries is a topic of ongoing debate. Irrespective of conservation benefits, a fundamental question is whether hatcheries will be able to function as they have in the past given anticipated future climate conditions. To begin to answer this question, we developed a deterministic modeling framework to evaluate how climate change may affect hatcheries that rear Pacific salmon. The framework considers the physiological tolerances for each species, incorporates a temperature-driven growth model, and uses two metrics commonly monitored by hatchery managers to determine the impacts of changes in water temperature and availability on hatchery rearing conditions. As a case study, we applied the model to the US Fish and Wildlife Service’s Winthrop National Fish Hatchery. We projected that hatchery environmental conditions remained within the general physiological tolerances for Chinook salmon in the 2040s (assuming A1B greenhouse gas emissions scenario), but that warmer water temperatures in summer accelerated juvenile salmon growth. Increased growth during summer coincided with periods when water availability should also be lower, thus increasing the likelihood of physiological stress in juvenile salmon. The identification of these climate sensitivities led to a consideration of potential mitigation strategies such as chilling water, altering rations, or modifying rearing cycles. The framework can be refined with new information, but in its present form, it provides a consistent, repeatable method to assess the vulnerability of hatcheries to predicted climate change.     

Monitoring Fish Contaminant Responses to Abatement Actions: Factors that Affect Recovery

Monitoring of contaminant accumulation in fish has been conducted in East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee since 1985. Bioaccumulation trends are examined over a twenty year period coinciding with major pollution abatement actions by a Department of Energy facility at the stream’s headwaters. Although EFPC is enriched in many contaminants relative to other local streams, only polychlorinated biphenyls (PCBs) and mercury (Hg) were found to accumulate in the edible portions of fish to levels of human health concern. Mercury concentrations in redbreast sunfish were found to vary with season of collection, sex and size of individual fish. Over the course of the monitoring, waterborne Hg concentrations were reduced >80%; however, this did not translate into a comparable decrease in Hg bioaccumulation at most sites. Mercury bioaccumulation in fish did respond to decreased inputs in the industrialized headwater reach, but paradoxically increased in the lowermost reach of EFPC. As a result, the downstream pattern of Hg concentration in fish changed from one resembling dilution of a headwater point source in the 1980s to a uniform distribution in the 2000s. The reason for this remains unknown, but is hypothesized to involve changes in the chemical form and reactivity of waterborne Hg associated with the removal of residual chlorine and the addition of suspended particulates to the streamflow. PCB concentrations in fish varied greatly from year-to-year, but always exhibited a pronounced downstream decrease, and appeared to respond to management practices that limited episodic inputs from legacy sources within the facility.     

An ecological model of the habitat mosaic in estuarine nursery areas: Part I—Interaction of dispersal theory and habitat variability in describing juvenile fish distributions

Identification of critical habitat in estuarine nursery areas is an important conservation and management objective. Habitat can be viewed as a mosaic of both temporally variable environmental features and spatially variable structural features that combine to define optimal habitat. Effective models of juvenile distributions should account for individual movement, as well as the full suite of habitat variability including both spatial and temporal components. We have extended a terrestrial model of small-scale movement patterns to describe habitat choices of an index juvenile fish in an estuarine nursery system. Movement of small juvenile fishes was found to be influenced by both spatial and temporal patterns in habitat quality, and it was a balanced mix of both that resulted in an optimal distribution. Fishes that perceive habitat on a scale much smaller than the scale of spatial heterogeneity may respond to temporal change as a movement cue allowing for more deterministic outcomes at larger scales despite perceptual limitations. These model outcomes suggest a hierarchical approach is best for describing habitat choice in juvenile fishes and this approach will be used in the future to explore individual and population responses to predictable habitat change.     

A simple plankton model for the Oregon upwelling ecosystem: Sensitivity and validation against time-series ocean data

Simple plankton models serve as useful platforms for testing our understanding of the mechanisms underlying ecosystem dynamics. A simple, one-dimensional plankton model was developed to describe the dynamics of nitrate, ammonium, two phytoplankton size-classes, meso-zooplankton, and detritus in the Oregon upwelling ecosystem. Computational simplicity was maintained by linking the biological model to a one-dimensional, cross-shelf physical model driven by the daily coastal upwelling index. The model sacrificed resolution of regional-scale and along-shore (north to south) processes and assumed that seasonal productivity is primarily driven by local cross-shelf Ekman transport of surface waters and upwelling of nutrient-rich water from depth.Our goals were to see how well a simple plankton model could capture the general temporal and spatial dynamics of the system, test system sensitivity to alternate parameter set values, and observe system response to the effective scale of potential retention mechanisms. Model performance across the central Oregon shelf was evaluated against two years (2000-2001) of chlorophyll and copepod time-series observations. While the modeled meso-zooplankton biomass was close in scale to the observed copepod biomass, phytoplankton was overestimated relative to that inferred from the observed surface chlorophyll concentration. Inshore, the system was most sensitive to the nutrient uptake kinetics of diatom-size phytoplankton and to the functional grazing response of meso-zooplankton. Meso-zooplankton was more sensitive to alternate parameter values than was phytoplankton. Reduction of meso-zooplankton cross-shelf advection rates (crudely representing behavioral retention mechanisms) reduced the scale of model error relative to the observed seasonal mean inshore copepod biomass but had little effect of the modeled meso-zooplankton biomass offshore nor upon phytoplankton biomass across the entire shelf.     

Leaf-cutter ants with worn mandibles cut half as fast,spend twice the energy,and tend to carry instead of cut

The importance of mechanical wear in the behavioral ecology and energetics of small organisms is an open question. We investigated wear in leaf-cutter ants, Atta cephalotes, because their cutting technique can be imitated and the leaves are the main energy source for the colony. We found that a razor-sharp (50-nm radius) “V-blade” that cuts leaves between the first and second mandibular teeth was dulled (∼10-μm radius) and often nearly worn away on foragers. We found that the force required to cut standard leaves, using mandibles removed from foragers cutting in the wild, varied by a factor of 2.5 with tooth wear, defined as the difference between pupal and actual tooth length. We also found that wear significantly reduced the cutting rate. From the distribution of wear among the cutting foragers, we estimated that the wild colony would have spent 44% less of both energy and time making the observed cuts if the cutters’ mandibles had all been pristine. Finally, wear correlated with behavioral differences—foragers with the most worn 10% of mandibles almost exclusively carried rather than cut. This previously unreported form of task partitioning suggests that eusociality may extend useful lifespans by making it possible to switch tasks as skills decline. We developed a model, assuming that ants do work at a constant rate proportional to their mass, to predict the cutting rate from head width, tooth wear, and force to cut leaves with a scalpel (R = 0.62), and we used this estimate to argue that the partitioning of cutting and carrying was sub-optimal but better than random. Wear’s strong effect on performance may promote wear-avoiding behavior and wear-resistant mandible composition; it may affect leaf selection and worker lifespan and it raises the possibility that wear is a similarly important constraint for many other small organisms.     

Lessons from Developing Methods to Study the Relationship of Energy and Water Savings to Housing Conditions and Resident Health

Abstract

Energy- and water-saving have been promoted as ways of saving money while there has been controversy about the effects (if any) of such measures on resident health. In public housing in the US, energy saving has taken the form of Energy Savings Performance Contracts (ESPC) that pay for renovations out of future savings. In an attempt to test feasibility and pilot research methods we conducted a study of the relationship between gas and water use, exterior heat sensor locations, and basement ventilation with indices developed from resident-reported living conditions and health symptoms in a single housing development. The data sources that we had available to us were not ideal. In particular, we were unable to obtain water use data that coincided in time with our health survey data. Also, we did not have enough surveys in buildings with high water or gas use and had to pool those buildings with other buildings for analysis. Nevertheless, we found several associations between our measures of energy use and resident reports of health symptoms. The associations that we found were generally in the direction that energy and water savings were associated with fewer symptoms and fewer environmental problems. There is a need for studies that obtain better input data but that generally follow the approach we developed.     

Multi-level coordination of climate change adaptation: by national hierarchical steering or by regional network governance?

The institutional structure and public service delivery apparatus required to meet the future effects of climate change already exist in Norway. However, there are huge challenges in coordinating these institutions at different authority levels for climate change adaptation purposes. Based upon a broad case study, this article presents how local actors consider the multi-level coordination of different levels of government and policy sectors to function today, which are the mechanisms that are used and what are the coordination challenges that are identified. Based upon the challenges revealed, this article discusses how best can the government-level institutions be organised for better goal attainment. We argue here that the elected regional level in Norway – the counties – has a huge potential to act as a multi-level coordination actor.     

Why Mami Wata matter: Local considerations for sustainable waterpower development policy in Central Africa

This paper is based on the author's fieldwork on the incorporation of local cultural understandings in the design of rural sustainability projects in the Democratic Republic of Congo. It explores several narratives about Mami Wata, mythological aquatic figures widely known in West and Central Africa, and their meanings for small-scale waterpower development projects, or micro-hydros. Careful examination of such narratives represents one way in which local conceptions and understandings can inform rural development policy, especially with regard to the social distribution of the benefits such projects aim to bring. When designing policies, development agents and agencies would do well to take these mythological and spiritual dimensions of local people's reality seriously rather than dismiss them as irrelevant, or simply as non-empirical phenomena and therefore without effects. The paper concludes with some concrete suggestions for policy action, paying special attention to how researchers and policymakers can work together to integrate local understandings more effectively into rural development strategies.